Stuttering, AdultNCT06011837
Effects of Altered Auditory Feedback on Speech Fluency
A study testing Altered Auditory Feedback in people with Stuttering, Adult, run by Massachusetts Institute of Technology at 1 site in United States.
Trial summary
The purpose of the study is to use altered auditory vocal feedback to increase fluency in people who stutter and to examine changes in this effect over the course of a one month period occurring outside the laboratory setting. Read more about this study
- Who is it for?
- Ages 18 to 100 years
- Conditions the study is for
- Stuttering, Adult
- What is being tested?
- Altered Auditory Feedback
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 100 participants
- Where
- 1 siteUnited States
- Study dates
- 26 May 2023to 1 Jun 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 100 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Identifies as a person who stutters
- Is US citizen or green card holder currently residing in the US
- Has one of the following Apple devices:
- iPhone with iOS 12.0 or later
- iPad with iPadOS 12.0 or later
- iPod touch with iOS 12.0 or later
Show all 10Show fewer
- Mac with macOS 11.0 or later and an Apple M1 chip or later
- Has a SEPARATE browser-supporting device with a microphone
- Is able to conduct the study in English
- Qualifies based on an initial screening evaluation (Greater than 2.5% Stuttering-Like Dysfluencies per syllable)
Who cannot join
- -
Trial locations and contacts
1 site in 1 country.
United States1 site
Massachusetts Institute of Technology
Cambridge, Massachusetts, 02139
About this study
The purpose of the study is to use altered auditory vocal feedback to increase fluency in people who stutter and to examine changes in this effect over the course of a one month period occurring outside the laboratory setting.
Read the detailed description
The Mumble Melody app applies voice transformations (or "modes") to a user's voice in real-time while they are speaking. The modes include Unaltered, Whisper, Reverberated, and Harmonious voice transformations. The Mumble Melody Longitudinal Study is a month-long online study in which the investigators will be investigating the longer term effects of using the Mumble Melody app for people who stutter. During the course of a month, eligible participants will use the Mumble Melody app daily for however long, on whichever modes, and in whichever settings they wish. Additionally, the investigators will be sending an online platform for participants to conduct weekly at-home testing sessions, in which they will be asked to record their voice during various speech tasks, both with and without the Mumble Melody app. During testing sessions, the investigators will collect voice recordings from participants.
Step 1: Participants will sign a consent form via Redcap. Participants will need an Apple device compatible with the Mumble Melody app.
Step 2: Participants will receive an additional form via Redcap through which they can input information about what device they will be using for the Mumble Melody study, as well as shipping information to receive wired headphones and a headphone jack (which are necessary to use the app).
Step 3: Participants conduct an initial screening session through an online platform, in which they respond to 3 90-second open questions and conduct a passage reading task. The investigators will be collecting voice recordings as they speak within the sessions.
Step 4: Participants' eligibility will be determined using the voice recordings received from step 3. The amount of stuttering-like events and total number of syllables within the recordings will determine if participants have a moderate to severe stutter, meaning they will be eligible for the study.
Step 5: Eligible participants are shipped wired headphones and a headphone jack adapter
Step 6: Participants will fill out an initial survey and optional OASES (Overall Assessment of the Speaker's Experience of Stuttering) assessment of through an online platform.
Step 7: Participants conduct a baseline testing session. During this testing session, participants will answer survey questions, record answers to 2 90-second open response questions without using the Mumble Melody app, follow a step-by-step guide to download and set up the Mumble Melody app, record answers to 2 90-second open response for each of the 4 modes on the Mumble Melody app, and finally record answers to 2 90-second open response questions without using the Mumble Melody app.
Step 8: Step 8: For the following 28 days, participants will be told to use the app as they wish. The investigators will collect app usage logs, which provide timestamps indicating which mode was used and length of use. Participants will receive an additional monetary reward if they use the app for at least 5 minutes for 4 out of 6 days each week.
Step 9: Participants conduct 4 testing sessions, one at the end of each week of the study (day 8, 15, 22, and 29). During each testing session, participants will answer survey questions, record answers to 2 90-second open response questions without using the Mumble Melody app, record answers to 2 90-second open response for each of the 4 modes on the Mumble Melody app, and finally record answers to 2 90-second open response questions without using the Mumble Melody app.
Step 10: After the study, participants will be sent a final survey asking questions on their experience throughout the study and their feedback for the app.
- Conditions
- Stuttering, Adult
- Being tested
- Altered Auditory Feedback
- Medical subject headings
- Stuttering
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Altered Auditory FeedbackDevice
Also called Musically Modulated Auditory Feedback, Mumble Melody
Mumble Melody is an application that leverages Altered Auditory Feedback (AAF). During AAF, a person's speech is altered in near-real time. Mumble Melody modulates the user's voice and plays it back to them while they are speaking. Included are Unaltered (raw voice), Whisper (voiceless sound), Reverb (cathedral sound), and Harmonized (robotic sound) voice transformations.
| Study group | Role | What they receive |
|---|---|---|
| Altered Auditory Feedback | Experimental | Participants in this arm will use the Mumble Melody application over the course of 1 month Receives: Device: Altered Auditory Feedback |
What is being measured
The primary outcome is the main question the study is designed to answer.
Significant change in fluency in one of four modes (Unaltered, Whisper, Reverb, Harmonize) between the baseline testing session and the end of week 4.
Fluency change From Baseline - Week 4 Measured by Stuttering-Like Dysfluencies within voice recordings from participants
Measured: Calculated at the end of the study for time points 1-week, 2-weeks, 3-weeks, and 4-weeks
Secondary outcomes (9)
Frequency of Mode Usage
Number of times participants use each modes per day throughout the study
Measured: Calculated every day for 4 weeks
Duration of Mode Usage
Length of times participants use different modes per day throughout the study
Measured: Calculated every day for 4 weeks
Survey data on experience using the application
A quality of experience survey for participants. This survey includes multiple questions and ratings as described in detail in the study protocol.
Measured: immediately after the intervention
Significant change in fluency in one of four modes (Unaltered, Whisper, Reverb, Harmonize) between the baseline testing session and end of week 1, 2, and 3.
Fluency change From Baseline - Week 1,2,3 Measured by Stuttering-Like Dysfluencies within voice recordings from participants
Measured: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Significant change in fluency in the Baseline (No Auditory Feedback) condition between baseline and end of week 1, 2, 3, and 4.
Fluency change From Baseline - Week 1,2,3,4 Measured by Stuttering-Like Dysfluencies within voice recordings from participants
Measured: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Significant change in fluency in the Final (No Auditory Feedback) condition between baseline and end of week 1, 2, 3, and 4.
Fluency change From Baseline - Week 1,2,3,4 Measured by Stuttering-Like Dysfluencies within voice recordings from participants
Measured: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Significant change in fluency for the Final (No Auditory Feedback) condition in comparison to the baseline (No Auditory Feedback) condition, for each testing session
Fluency change From Baseline (No Auditory Feedback) - Final (No Auditory Feedback) for each Testing Session Measured by Stuttering-Like Dysfluencies within voice recordings from participants
Measured: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Significant change in fluency for each mode in comparison to the baseline (No Auditory Feedback) condition, for each testing session
Fluency change From Baseline (No Auditory Feedback) - each Mode for each Testing Session Measured by Stuttering-Like Dysfluencies within voice recordings from participants
Measured: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Significant change in fluency for each non- control mode (Whisper, Reverb, Harmonize) in comparison to the control mode (Unaltered), for each testing session
Fluency change From Unaltered Mode - Whisper/Reverb/Harmonize modes for each Testing Session Measured by Stuttering-Like Dysfluencies within voice recordings from participants
Measured: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Aug 2023
- Study start26 May 2023
- Primary completion15 Jun 2024
- Study completion1 Jun 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Stuttering, AdultStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Supportive care
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 100 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Massachusetts Institute of Technology
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Satrajit Ghosh, PhD, Principal investigator, Massachusetts Institute of Technology
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06011837
- Sponsor's protocol ID
- 1906848293
- Status last verified
- May 2026
- First submitted
- 9 May 2023
- Last updated
- 14 May 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Subjects can choose to consent to having their audio recordings and survey answers shared with the researchers of this study and other qualified researchers.
Study at a glance
From the registry record, last updated by the sponsor on 14 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Altered Auditory Feedback on Speech Fluency
- ClinicalTrials.gov ID
- NCT06011837
- Acronym / sponsor ID
- 1906848293
- Conditions
- Stuttering, Adult
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 100 participants (estimated)
- Lead sponsor
- Massachusetts Institute of TechnologyUniversity, hospital or other
- Study start
- 26 May 2023 (actual)
- Primary completion
- 15 Jun 2024 (actual)
- Study completion
- 1 Jun 2026 (estimated)
- First posted
- 25 Aug 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of the study is to use altered auditory vocal feedback to increase fluency in people who stutter and to examine changes in this effect over the course of a one month period occurring outside the laboratory setting.
Detailed description
The Mumble Melody app applies voice transformations (or "modes") to a user's voice in real-time while they are speaking. The modes include Unaltered, Whisper, Reverberated, and Harmonious voice transformations. The Mumble Melody Longitudinal Study is a month-long online study in which the investigators will be investigating the longer term effects of using the Mumble Melody app for people who stutter. During the course of a month, eligible participants will use the Mumble Melody app daily for however long, on whichever modes, and in whichever settings they wish. Additionally, the investigators will be sending an online platform for participants to conduct weekly at-home testing sessions, in which they will be asked to record their voice during various speech tasks, both with and without the Mumble Melody app. During testing sessions, the investigators will collect voice recordings from participants.
Step 1: Participants will sign a consent form via Redcap. Participants will need an Apple device compatible with the Mumble Melody app.
Step 2: Participants will receive an additional form via Redcap through which they can input information about what device they will be using for the Mumble Melody study, as well as shipping information to receive wired headphones and a headphone jack (which are necessary to use the app).
Step 3: Participants conduct an initial screening session through an online platform, in which they respond to 3 90-second open questions and conduct a passage reading task. The investigators will be collecting voice recordings as they speak within the sessions.
Step 4: Participants' eligibility will be determined using the voice recordings received from step 3. The amount of stuttering-like events and total number of syllables within the recordings will determine if participants have a moderate to severe stutter, meaning they will be eligible for the study.
Step 5: Eligible participants are shipped wired headphones and a headphone jack adapter
Step 6: Participants will fill out an initial survey and optional OASES (Overall Assessment of the Speaker's Experience of Stuttering) assessment of through an online platform.
Step 7: Participants conduct a baseline testing session. During this testing session, participants will answer survey questions, record answers to 2 90-second open response questions without using the Mumble Melody app, follow a step-by-step guide to download and set up the Mumble Melody app, record answers to 2 90-second open response for each of the 4 modes on the Mumble Melody app, and finally record answers to 2 90-second open response questions without using the Mumble Melody app.
Step 8: Step 8: For the following 28 days, participants will be told to use the app as they wish. The investigators will collect app usage logs, which provide timestamps indicating which mode was used and length of use. Participants will receive an additional monetary reward if they use the app for at least 5 minutes for 4 out of 6 days each week.
Step 9: Participants conduct 4 testing sessions, one at the end of each week of the study (day 8, 15, 22, and 29). During each testing session, participants will answer survey questions, record answers to 2 90-second open response questions without using the Mumble Melody app, record answers to 2 90-second open response for each of the 4 modes on the Mumble Melody app, and finally record answers to 2 90-second open response questions without using the Mumble Melody app.
Step 10: After the study, participants will be sent a final survey asking questions on their experience throughout the study and their feedback for the app.
Study design
- Primary purpose
- Supportive care
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Altered Auditory Feedback | Experimental | Device: Altered Auditory FeedbackParticipants in this arm will use the Mumble Melody application over the course of 1 month |
Who may qualify
- Ages
- 18 to 100 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (10 listed)
- Identifies as a person who stutters
- Is US citizen or green card holder currently residing in the US
- Has one of the following Apple devices:
- iPhone with iOS 12.0 or later
- iPad with iPadOS 12.0 or later
Key exclusion criteria (1 listed)
- -
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Altered Auditory FeedbackAlso: Musically Modulated Auditory Feedback, Mumble MelodyMumble Melody is an application that leverages Altered Auditory Feedback (AAF). During AAF, a person's speech is altered in near-real time. Mumble Melody modulates the user's voice and plays it back to them while they are speaking. Included are Unaltered (raw voice), Whisper (voiceless sound), Reverb (cathedral sound), and Harmonized (robotic sound) voice transformations. | Device | Altered Auditory Feedback |
Primary outcome
Significant change in fluency in one of four modes (Unaltered, Whisper, Reverb, Harmonize) between the baseline testing session and the end of week 4.
Time frame: Calculated at the end of the study for time points 1-week, 2-weeks, 3-weeks, and 4-weeks
Fluency change From Baseline - Week 4 Measured by Stuttering-Like Dysfluencies within voice recordings from participants
9 secondary outcomes
Frequency of Mode Usage
Time frame: Calculated every day for 4 weeks
Duration of Mode Usage
Time frame: Calculated every day for 4 weeks
Survey data on experience using the application
Time frame: immediately after the intervention
Significant change in fluency in one of four modes (Unaltered, Whisper, Reverb, Harmonize) between the baseline testing session and end of week 1, 2, and 3.
Time frame: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Significant change in fluency in the Baseline (No Auditory Feedback) condition between baseline and end of week 1, 2, 3, and 4.
Time frame: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Significant change in fluency in the Final (No Auditory Feedback) condition between baseline and end of week 1, 2, 3, and 4.
Time frame: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Significant change in fluency for the Final (No Auditory Feedback) condition in comparison to the baseline (No Auditory Feedback) condition, for each testing session
Time frame: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Significant change in fluency for each mode in comparison to the baseline (No Auditory Feedback) condition, for each testing session
Time frame: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Significant change in fluency for each non- control mode (Whisper, Reverb, Harmonize) in comparison to the control mode (Unaltered), for each testing session
Time frame: Calculated at the end of the study for time points: Baseline, 1-week, 2-weeks, 3-weeks, and 4-weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 14 May 2026.
- Individual participant dataSharing planned: Yes. Subjects can choose to consent to having their audio recordings and survey answers shared with the researchers of this study and other qualified researchers.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Satrajit Ghosh, PhD principal investigator
Massachusetts Institute of Technology
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Altered Auditory Feedback in people with Stuttering, Adult, run by Massachusetts Institute of Technology at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 10 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 14 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Significant change in fluency in one of four modes (Unaltered, Whisper, Reverb, Harmonize) between the baseline testing session and the end of week 4. (time frame: Calculated at the end of the study for time points 1-week, 2-weeks, 3-weeks, and 4-weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 May 2026.